Irrigation systems are used to provide water to a wide variety of devices, including, for example, spray nozzles, sprinkler heads, and drip hoses. Such systems generally make use of control valves to command the flow of water through the system, pressure regulators to even out variations in source water pressure, and filters to remove debris and particulate matter from the water flow.
Solenoid controlled on/off valves for use in irrigation systems are well known. For example, a solenoid-actuated valve uses a solenoid to command a small flow of control water, which, in turn, controls a larger flow of water to attached irrigation devices. Such solenoid-actuated valves often include relatively small passageways for the flow of control water and require the filtering of the control water to insure the removal of particulate matter which could block flow through the relatively small passageways. A filter may be placed upstream to filter the control water stream.
Water filters are also used in a wide range of applications to remove particulate matter from an irrigation water flow stream. Irrigation water supplies may contain fine particulate matter and debris capable of obstructing flow through sprinkler heads or low-flow emitter devices such as drip hoses. Thus, it is necessary to filter the irrigation water supply upstream of attached irrigation devices.
The aggregation of material on the upstream side of a filter can lead to a pressure drop across the filter medium and can significantly reduce water flow through the filter and adversely impact the performance of the irrigation system. Thus, it is also beneficial to be able to clean the filter medium. One known device uses scraper blades to clean the upstream surface of a filter each time the solenoid-actuated valve is opened or closed. Another known device is a self-cleaning filter device which is placed downstream from a control valve. This device filters the irrigation water stream and automatically cleans and back washes a filter on each on and off cycle of an upstream control valve.
Prior irrigation devices provide filters for the irrigation water or for the control water, but not both. Irrigation control devices and filters are generally located in the field, and it can be inconvenient and costly to manually clean the filters and purge them of debris and other particulate matter. Thus, there is a need for an improved self-cleaning filter assembly which cleans a filter on each on and off cycle of a control valve and which filters both the control water for use by a control valve and the irrigation water for use by the irrigation system.